190910-71-5Relevant academic research and scientific papers
H+/AuPPh3+ Exchange for the Hydride Complexes CpMoH(CO)2(L) (L = PMe3, PPh3, CO). Formation and Structure of [Cp(CO)2(PMe3)Mo(AuPPh3)2] +[BF4]-
Galassi, Rossana,Poli, Rinaldo,Quadrelli, E. Alessandra,Fettinger, James C.
, p. 3001 - 3007 (1997)
The reaction of CpMoH(CO)2L with AuPPh3 +BF4- in THF at -40 °C proceeds directly to the MoAu2 cluster compounds [CpMo(CO)2L(AuPPh3)2]+BF 4- (L = PMe3 (1), PPh3 (2)) with release of protons. A 1:1 reaction leaves 50% of the starting hydride unreacted. At lower temperature, however, the formation of a [CpMo(CO)2-(PMe3)(μ-H)(AuPPh3)]+ intermediate is observed. This compound evolves to the cation of 1 and CpMoH(CO)2-(PMe3) upon warming and is deprotonated by 2,6-lutidine to afford CpMo(CO)2(PMe3)(AuPPh3). The X-ray structure of 1 can be described as a four-legged piano stool with the PMe3 and the η2-(AuPPh3)2 ligands occupying relative trans positions. [Cp(CO)2(PMe3)Mo(AuPPh3)2] +[BF4]- (Mr = 1298.41): monoclinic, space group P21/ n, a= 18.1457(13) A?, b = 9.7811(7) A?, c = 26.096(2) A?, β= 105.086(5)°, V = 4472.0(5) ?3, Z = 4. The reaction of CpMoH(CO)2(PMe3) with 3 equiv of AuPPh3+ affords a MoAu3 cluster, [CpMo(CO)2(PMe3)-(AuPPh3)3] 2+ (3), in good yields under kinetically controlled conditions. Under thermodynamically controlled conditions, 3 dissociates extensively into 1 and free AuPPh3+.. It is proposed that the hydride ligand helps build higher nuclearity Mo - Au clusters. The difference in reaction pathways for the interaction of AuPPh3+ with CpMoH(CO)2L when L = PR3 or CO and for the interaction of CpMoH(CO)2(PMe3 with E+ when E = H, Ph3C or AuPPh3 is discussed. The lower acidity and greater aurophilicity of the [CpMo(CO)2L(μ-H)(AuPPh3)]+ intermediate when L = PMe3 favor attack by AuPPh3+ before deprotonation.
